HP48 (thing)

The HP48 (g) was my only friend all throughout high school. I used it to write little programs that would take me into another life where I was happy. The reverse polish notation that it used made sure that no one else wanted to steal this calculator because they couldn't figure out how to use the damn thing. This, and its ability to do 3d graphs and play Tetris via infrared prevented me from committing suicide.